U.S. patent application number 14/976273 was filed with the patent office on 2016-08-11 for optical device and a light source module having the same.
The applicant listed for this patent is SAMSUNG ELECTRONICS CO., LTD.. Invention is credited to SANG WOO HA, WON SOO JI, JONG PIL WON.
Application Number | 20160230954 14/976273 |
Document ID | / |
Family ID | 56565835 |
Filed Date | 2016-08-11 |
United States Patent
Application |
20160230954 |
Kind Code |
A1 |
HA; SANG WOO ; et
al. |
August 11, 2016 |
OPTICAL DEVICE AND A LIGHT SOURCE MODULE HAVING THE SAME
Abstract
An optical device includes a first surface including a light
incident surface onto which light is incident, and a second surface
which emits light passing through the light incident surface. The
light incident surface includes a first curved surface and a second
curved surface. The first curved surface is disposed in a recess in
a central portion of the light incident surface and recessed toward
the second surface, the second curved surface being connected to
the first curved surface in the recess and extended from the
recess. The first and second curved surfaces have an inflection
point at a contact point at which the first and second curved
surfaces contact each other. The second surface opposes the first
surface, and the first and second surfaces form a biconvex lens
structure.
Inventors: |
HA; SANG WOO; (SEONGNAM-SI,
KR) ; JI; WON SOO; (HWASEONG-SI, KR) ; WON;
JONG PIL; (YONGIN-SI, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SAMSUNG ELECTRONICS CO., LTD. |
SUWON-SI |
|
KR |
|
|
Family ID: |
56565835 |
Appl. No.: |
14/976273 |
Filed: |
December 21, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F21K 9/69 20160801; F21W
2131/10 20130101; F21Y 2115/10 20160801; G02B 19/0061 20130101;
F21Y 2103/10 20160801; F21K 9/27 20160801; F21V 5/048 20130101;
F21K 9/23 20160801 |
International
Class: |
F21V 5/04 20060101
F21V005/04; F21K 99/00 20060101 F21K099/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 9, 2015 |
KR |
10-2015-0019466 |
Claims
1. An optical device comprising: a first surface including a light
incident surface onto which light is incident; and a second surface
which emits light passing through the light incident surface,
wherein the light incident surface includes a first curved surface
and a second curved surface, the first curved surface being
disposed in a recess in a central portion of the light incident
surface and recessed toward the second surface, the second curved
surface being connected to the first curved surface in the recess
and extended from the recess, and the first and second curved
surfaces have an inflection point at a contact point at which the
first and second curved surfaces contact each other, and wherein
the second surface opposes the first surface, and the first and
second surfaces form a biconvex lens structure.
2. The optical device of claim 1, wherein an optical axis passes
through the recess.
3. The optical device of claim 1, wherein a shape of the light
incident surface satisfies conditions 1 to 3: Condition 1:
dR/d.theta.<0 for .theta..ltoreq.55.degree. Condition 2:
dR/d.theta.=0 for 55.degree.<.theta.<65.degree. Condition 3:
dR/d.theta.>0 for 65.degree..ltoreq..theta., where, when an
intersection point between an optical axis passing through the
recess and a light emission surface of a light source is a
reference point "O", "R" refers to a straight line connecting the
reference point "O" and a point of the light incident surface to
each other, and ".theta." refers to an angle formed by the straight
line "R" with respect to the optical axis.
4. The optical device of claim 3, wherein the shape of the light
incident surface satisfies conditions 4 to 6: Condition 4:
.theta.2/.theta.1>1 for .theta.1.ltoreq.55.degree. Condition 5:
.theta.2/.theta.1=1 for 55.degree.<.theta.1<65.degree.
Condition 6: .theta.2/.theta.1<1 for 65.degree..ltoreq..theta.1,
where ".theta.1" refers to a light emission angle formed by light
emitted from the light source with respect to the optical axis, and
".theta.2" refers to a refraction angle of the light having the
light emission angle ".theta.1", which is refracted from the light
incident surface toward the second surface, with respect to the
optical axis.
5. The optical device of claim 1, further comprising a flange
portion disposed between the first surface and the second surface
at an edge of the optical device, and a thickness "Tf" of the
optical device measured from a bottom surface of the optical device
to a center of the flange portion in a vertical direction
corresponds to 1/3 to 1/2 of an overall thickness "Tt" of the
optical device.
6. The optical device of claim 1, wherein, when an intersection
point between an optical axis passing through the recess and a
light emission surface of a light source is a reference point "O",
a first ray of light emitted from "O" and having a first angle with
respect to the optical axis is refracted downward by the light
incident surface, and a second ray of light emitted from "O" and
having a second angle with respect to the optical axis is refracted
upward by the light incident surface, wherein the first angle is
smaller than the second angle.
7. The optical device of claim 1, wherein the second surface
comprises a concave portion recessed toward the recess of the first
surface, and a convex portion extended from an edge of the concave
portion to an edge of the optical device.
8. The optical device of claim 1, further comprising a support
portion disposed on the first surface.
9. An optical device comprising: a first surface including a recess
disposed in a central portion of the first surface; and a second
surface that faces the first surface to form a biconvex lens,
wherein the recess is recessed toward the second surface and
includes a light incident surface onto which light is incident, the
light incident surface includes a first curved surface and a second
curved surface, the first curved surface being disposed in the
recess in the central portion of the first surface and recessed
toward the second surface, the second curved surface being
connected to the first curved surface in the recess and extended
from the recess, and the first and second curved surfaces have an
inflection point at a contact point at which the first and second
curved surfaces contact each other.
10. The optical device of claim 9, wherein a sidewall of the recess
has an approximate S-shaped vertical cross-section.
11. A light source module comprising: a light source; and an
optical device including a first surface and a second surface,
wherein the first surface is disposed above the light source and
includes a recess formed in a central portion of the first surface
and recessed toward the second surface, and the second surface
opposes the first surface to form a biconvex lens, wherein the
recess includes a light incident surface onto which light from the
light source is incident, the light incident surface includes a
first curved surface and a second curved surface, the first curved
surface being disposed in the recess in the central portion of the
first surface and recessed toward the second surface, the second
curved surface being connected to the first curved surface in the
recess and extended from the recess, and the first and second
curved surfaces have an inflection point at a contact point where
the first and second curved surfaces contact each other.
12. The light source module of claim 11, wherein a size of an
opening of the recess is greater than a size of the light
source.
13. The light source module of claim 11, wherein the light source
is a light emitting diode (LED) chip or a light emitting diode
package in which the light emitting diode chip is disposed.
14. The light source module of claim 13, wherein the light source
comprises an encapsulation part encapsulating the light emitting
diode chip.
15. The light source module of claim 11, further comprising a
substrate on which the light source and the optical device are
disposed.
16. An optical device comprising: a first surface comprising, in
cross-sectional view, a first convex portion, a second convex
portion, and a first concave portion disposed therebetween; and a
second surface comprising, in the cross-sectional view, a third
convex portion, a fourth convex portion, and a second concave
portion disposed therebetween, wherein the first surface and the
second surface face each other, wherein the first concave portion
and the second concave portion protrude toward each other, wherein
the first concave portion includes a first sidewall and a second
sidewall that face each other, wherein the first sidewall includes
a first region and a second region, wherein light passing through
the first region is refracted downward with respect to its original
direction, and light passing through the second region is refracted
upward with respect to its original direction.
17. The optical device of claim 16, wherein the first region of the
first sidewall forms a bottom of a recess and the second region of
the first sidewall forms an opening of the recess.
18. The optical device of claim 16, wherein the first surface and
the second surface are connected to each other with a pair of
flanges.
19. The optical device of claim 16, wherein light is emitted
through the first surface to the second surface.
20. The optical device of claim 19, wherein the light is incident
to the first concave portion of the first surface.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority under 35 U.S.C. .sctn.119
to Korean Patent Application No. 10-2015-0019466, filed on Feb. 9,
2015, in the Korean Intellectual Property Office, the disclosure of
which is incorporated by reference herein in its entirety.
TECHNICAL FIELD
[0002] The present inventive concept relates to an optical device
and a light source module having the same.
DISCUSSION OF THE RELATED ART
[0003] A wide-beam angle lens is a type of lens used in light
emitting device packages to allow light to be widely diffused.
Light incident to a central portion of the wide-beam angle lens is
diffused laterally by refraction. However, in a case in which the
light incident to the lens is not uniformly distributed due to
various types of light sources included in light emitting device
packages, a partial increase in brightness distribution may occur.
As such, optical non-uniformity defects such as Mura may occur.
SUMMARY
[0004] According to an exemplary embodiment of the present
inventive concept, an optical device includes a first surface
including a light incident surface onto which light is incident,
and a second surface which emits light passing through the light
incident surface. The light incident surface includes a first
curved surface and a second curved surface. The first curved
surface is disposed in a recess in a central portion of the light
incident surface and recessed toward the second surface, the second
curved surface being connected to the first curved surface in the
recess and extended from the recess. The first and second curved
surfaces have an inflection point at a contact point at which the
first and second curved surfaces contact each other. The second
surface opposes the first surface, and the first and second
surfaces form a biconvex lens structure.
[0005] In an exemplary embodiment of the present inventive concept,
an optical axis passes through the recess.
[0006] In an exemplary embodiment of the present inventive concept,
a shape of the light incident surface satisfies conditions 1 to
3:
[0007] Condition 1: dR/d.theta.<0 for
.theta..ltoreq.55.degree.
[0008] Condition 2: dR/d.theta.=0 for
55.degree.<.theta.<65.degree.
[0009] Condition 3: dR/d.theta.>0 for
65.degree..ltoreq..theta.
[0010] where, when an intersection point between an optical axis
passing through the recess and a light emission surface of a light
source is defined as a reference point "O", "R" refers to a
straight line connecting the reference point and a point of the
light incident surface to each other, and ".theta." refers to an
angle formed by the straight line "R" with respect to the optical
axis.
[0011] In an exemplary embodiment of the present inventive concept,
the shape of the light incident surface satisfies conditions 4 to
6:
[0012] Condition 4: .theta.2/.theta.1>1 for
.theta.1.ltoreq.55.degree.
[0013] Condition 5: .theta.2/.theta.1=1 for
55.degree.<.theta.1<65.degree.
[0014] Condition 6: .theta.2/.theta.1<1 for
65.degree..ltoreq..theta.1
[0015] where ".theta.1" refers to a light emission angle formed by
light emitted from the light source with respect to the optical
axis, and ".theta.2" refers to a refraction angle of the light
having the light emission angle ".theta.1", which is refracted from
the light incident surface toward the second surface, with respect
to the optical axis.
[0016] In an exemplary embodiment of the present inventive concept,
the optical device further includes a flange portion disposed
between the first surface and the second surface at an edge of the
optical device, and a thickness "Tf" of the optical device measured
from a bottom surface of the optical device to a center of the
flange portion in a vertical direction corresponds to 1/3 to 1/2 of
an overall thickness "Tt" of the optical device.
[0017] In an exemplary embodiment of the present inventive concept,
when an intersection point between an optical axis passing through
the recess and a light emission surface of a light source is a
reference point "O", a first ray of light emitted from "O" and
having a first angle with respect to the optical axis is refracted
downward by the light incident surface, and a second ray of light
emitted from "O" and having a second angle with respect to the
optical axis is refracted upward by the light incident surface. The
first angle is smaller than the second angle.
[0018] In an exemplary embodiment of the present inventive concept,
the second surface includes a concave portion recessed toward the
recess of the first surface, and a convex portion extended from an
edge of the concave portion to an edge of the optical device.
[0019] In an exemplary embodiment of the present inventive concept,
the optical device further includes a support portion disposed on
the first surface.
[0020] According to an exemplary embodiment of the present
inventive concept, an optical device includes a first surface
including a recess disposed in a central portion of the first
surface, and a second surface that faces the first surface to form
a biconvex lens. The recess is recessed toward the second surface
and includes a light incident surface onto which light is incident.
The light incident surface includes a first curved surface and a
second curved surface, the first curved surface being disposed in
the recess in the central portion of the first surface and recessed
toward the second surface, the second curved surface being
connected to the first curved surface in the recess and extended
from the recess. The first and second curved surfaces have an
inflection point at a contact point at which the first and second
curved surfaces contact each other.
[0021] In an exemplary embodiment of the present inventive concept,
a sidewall of the recess has an approximate S-shaped vertical
cross-section.
[0022] According to an exemplary embodiment of the present
inventive concept, a light source module includes a light source,
and an optical device including a first surface and a second
surface. The first surface is disposed above the light source and
includes a recess formed in a central portion of the first surface
and recessed toward the second surface, and the second surface
opposes the first surface to form a biconvex lens. Wherein the
recess includes a light incident surface onto which light from the
light source is incident. The light incident surface includes a
first curved surface and a second curved surface, the first curved
surface being disposed in the recess in the central portion of the
first surface and recessed toward the second surface, the second
curved surface being connected to the first curved surface in the
recess and extended from the recess. The first and second curved
surfaces have an inflection point at a contact point where the
first and second curved surfaces contact each other.
[0023] In an exemplary embodiment of the present inventive concept,
a size of an opening of the recess is greater than a size of the
light source.
[0024] In an exemplary embodiment of the present inventive concept,
the light source is a light emitting diode (LED) chip or a light
emitting diode package in which the light emitting diode chip is
disposed.
[0025] In an exemplary embodiment of the present inventive concept,
the light source includes an encapsulation part encapsulating the
light emitting diode chip.
[0026] In an exemplary embodiment of the present inventive concept,
the light source module further includes a substrate on which the
light source and the optical device are disposed.
[0027] According to an exemplary embodiment of the present
inventive concept, an optical device includes a first surface
comprising, in cross-sectional view, a first convex portion, a
second convex portion, and a first concave portion disposed
therebetween, and a second surface comprising, in the
cross-sectional view, a third convex portion, a fourth convex
portion, and a second concave portion disposed therebetween. The
first surface and the second surface face each other. The first
concave portion and the second concave portion protrude toward each
other. The first concave portion includes a first sidewall and a
second sidewall that face each other. The first sidewall includes a
first region and a second region. Light passing through the first
region is refracted downward with respect to its original
direction, and light passing through the second region is refracted
upward with respect to its original direction.
[0028] In an exemplary embodiment of the present inventive concept,
the first region of the first sidewall forms a bottom of a recess
and the second region of the first sidewall forms an opening of the
recess.
[0029] In an exemplary embodiment of the present inventive concept,
the first surface and the second surface are connected to each
other with a pair of flanges.
[0030] In an exemplary embodiment of the present inventive concept,
light is emitted through the first surface to the second
surface.
[0031] In an exemplary embodiment of the present inventive concept,
the light is incident to the first concave portion of the first
surface.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] The above and other features of the present inventive
concept will become more apparent by describing in detail exemplary
embodiments thereof in conjunction with the accompanying drawings,
in which:
[0033] FIG. 1 is a schematic perspective view of a light source
module including an optical device, according to an exemplary
embodiment of the present inventive concept;
[0034] FIG. 2 is a cross-sectional view of FIG. 1, according to an
exemplary embodiment of the present inventive concept;
[0035] FIG. 3 is a cross-sectional view schematically illustrating
an enlarged light incident surface of the optical device of FIG. 2,
according to an exemplary embodiment of the present inventive
concept;
[0036] FIG. 4 is a cross-sectional view illustrating a relationship
between an angle of incidence and a refraction angle of the light
incident surface of the optical device of FIG. 3, according to an
exemplary embodiment of the present inventive concept;
[0037] FIG. 5 is a cross-sectional view schematically illustrating
an optical path of light emitted from the light source of FIG. 2
and passing through the optical device of FIG. 2, according to an
exemplary embodiment of the present inventive concept;
[0038] FIG. 6A is a cross-sectional view schematically illustrating
an optical path of light refracted at a first surface of the
optical device of FIG. 2 and emitted externally, according to an
exemplary embodiment of the present inventive concept;
[0039] FIG. 6B is a cross-sectional view schematically illustrating
an optical path of light refracted at a first surface of the
optical device of FIG. 2 and emitted externally, according to an
exemplary embodiment of the present inventive concept;
[0040] FIG. 7A is a cross-sectional view schematically illustrating
a light source module, according to an exemplary embodiment of the
present inventive concept;
[0041] FIG. 7B is a plan view schematically illustrating the light
source module of FIG. 7A, according to an exemplary embodiment of
the present inventive concept;
[0042] FIG. 8 is a schematic perspective view illustrating a state
in which a light source and an optical device are mounted on a
substrate of FIG. 7A, according to an exemplary embodiment of the
present inventive concept;
[0043] FIG. 9 is a cross-sectional view schematically illustrating
a light source, according to an exemplary embodiment of the present
inventive concept;
[0044] FIG. 10 illustrates a CIE 1931 chromaticity coordinates
system for illustrating a wavelength conversion material employable
in an exemplary embodiment of the present inventive concept;
[0045] FIG. 11 is a schematic diagram illustrating a
cross-sectional structure of a quantum dot (QD), according to an
exemplary embodiment of the present inventive concept;
[0046] FIG. 12 is a cross-sectional view illustrating a light
emitting diode (LED) chip used as a light source, according to an
exemplary embodiment of the present inventive concept;
[0047] FIG. 13A is a plan view illustrating an LED chip used as a
light source, according to an exemplary embodiment of the present
inventive concept;
[0048] FIG. 13B is a side cross-sectional view of the LED chip of
FIG. 13A, taken along line I-I' of FIG. 13A, according to an
exemplary embodiment of the present inventive concept;
[0049] FIG. 14 is a cross-sectional view illustrating an LED chip
used as a light source, according to an exemplary embodiment of the
present inventive concept;
[0050] FIG. 15 is a schematic perspective view and a
cross-sectional view illustrating an LED chip, according to an
exemplary embodiment of the present inventive concept;
[0051] FIG. 16 is a schematic cross-sectional view of a lighting
device, according to an exemplary embodiment of the present
inventive concept;
[0052] FIG. 17 is a schematic exploded perspective view of a
bulb-type lighting device, according to an exemplary embodiment of
the present inventive concept; and
[0053] FIG. 18 is a schematic exploded perspective view of a bar
type lighting device, according to an exemplary embodiment of the
present inventive concept;
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0054] Exemplary embodiments of the present inventive concept will
now be described more fully hereinafter with reference to the
accompanying drawings. The present inventive concept may, however,
be embodied in different forms and should not be construed as
limited to the embodiments set forth herein. In the drawings, the
sizes and relative sizes of layers and regions may be exaggerated
for clarity.
[0055] It will be understood that when an element or layer is
referred to as being "on," "connected to" or "coupled to" another
element or layer, it can be directly on, connected, or coupled to
the other element or layer, or intervening elements or layers may
be present.
[0056] As used herein, the singular forms "a," "an" and "the" are
intended to include the plural forms as well, unless the context
clearly indicates otherwise. It will be further understood that
terms such as those defined in commonly used dictionaries should be
interpreted as having a meaning that is consistent with their
meaning in the context of the relevant art and will not be
interpreted in an idealized or overly formal sense unless expressly
so defined herein.
[0057] With reference to FIGS. 1 and 2, optical light source module
including an optical device according to an exemplary embodiment of
the present inventive concept will be described. FIG. 1 is a
schematic perspective view of a light source module including an
optical device, according to an exemplary embodiment of the present
inventive concept. FIG. 2 is a cross-sectional view of FIG. 1,
according to an exemplary embodiment of the present inventive
concept.
[0058] With reference to FIGS. 1 and 2, a light source module 1,
according to an exemplary embodiment of the present inventive
concept, may include a light source 10 and an optical device 20
disposed above the optical source 10. In addition, the light source
module 1 may include a substrate 30 on which the light source 10
and the optical device 20 are mounted.
[0059] The light source 10 may be provided as a photoelectric
device for generating light having a predetermined wavelength
through externally-supplied driving power. For example, the light
source 10 may include a semiconductor light emitting diode (LED)
having an n-type semiconductor layer, a p-type semiconductor layer,
and an active layer disposed therebetween.
[0060] The light source 10 may emit blue light, green light or red
light, according to a material contained in the light source 10 or
according to a combination of phosphor with a material contained in
the light source 10. The light source 10 may also emit white light,
ultraviolet light, or the like. A detailed configuration and
structure of the light source 10 will be described in detail
below.
[0061] The optical device 20 may be disposed above the light source
10 to cover the light source 10. The optical device 20 may adjust
an angle in a spread of beams of light emitted from the light
source 10. For example, the optical device 20 may include a
wide-beam angle lens implementing a wide angle in a spread of light
beams by allowing beams of light emitted by the light source 10 to
be widely spread.
[0062] FIGS. 2 to 4 illustrate the optical device 20, according to
an exemplary embodiment of the present inventive concept. As
illustrated in FIG. 2, the optical device 20 may include a first
surface 21 having a light incident surface 23 onto which light
emitted from the light source 10 is incident, and a second surface
22 for emitting the light transmitted to the optical device 20
through the light incident surface 23 externally.
[0063] The optical device 20 may include a flange portion 25
corresponding to an outer edge of the optical device 20 between the
first surface 21 and the second surface 22. The flange portion 25
may be formed as an outermost protruding portion and may have a
predetermined thickness along a circumference of the optical device
20. The first surface 21 and the second surface 22 may include the
flange portion 25 therebetween and may be separated from each other
by the flange portion 25.
[0064] The optical device 20 may have a substantially biconvex lens
structure in which the first surface 21 facing the light source 10
protrudes in a direction toward the light source 10 in a convex
manner. The second surface 22 opposing the first surface 21
protrudes in a direction opposite to a direction in which the first
surface 21 protrudes, in a convex manner. In other words, the
optical device 20 may have a biconvex shape along a plane that is
substantially perpendicular to the optical axis Z. The biconvex
shape includes the first surface 21 which is a convex surface and
the second surface 22 which is also a convex surface and opposite
to the first surface 21. Light emitted from the light source 10
enters the optical device 20 through the light incident surface 23
of the first surface 21 and exits the optical device 20 through the
second surface 22.
[0065] The optical device 20 may have a structure in which a
thickness Tf thereof, from a bottom surface of the optical device
20 to a center of the flange portion 25, corresponds to about 1/3
to about 1/2 of an overall thickness Tt of the optical device
20.
[0066] The first surface 21 may be a surface provided above the
light source 10 to face the light source 10 and may correspond to a
bottom surface of the optical device 20. A central portion of the
first surface 21 through which an optical axis Z passes may be
recessed toward the second surface 22, to form a recess portion 24
forming the light incident surface 23. In other words, the first
surface 21 is a bottom surface of the optical device 20 and faces
the light source 10. The central portion of the first surface 21,
which corresponds to the light incident surface 23, may be
partially concave and partially convex. Light emitted from the
light source 10 enters the optical device 20 through the light
incident surface 23. The central portion of the first surface 21
also corresponds to the recess portion 24.
[0067] The recess portion 24 may have a rotationally symmetrical
structure about the optical axis Z passing through a center of the
optical device 20, and a surface of the recess portion 24 may be
defined as the light incident surface 23 onto which light emitted
from the light source 10 is incident. Thus, light generated by the
light source 10 may pass through the light incident surface 23 to
enter the interior of the optical device 20.
[0068] The recess portion 24 may be formed inwardly in the optical
device 20 in a direction inwardly from the first surface 21. In an
opening of the recess portion 24, a diameter of an end portion
thereof, for example, the size of a transverse cross-section
thereof exposed to the first surface 21 may be greater than that of
the light source 10. In other words, the recess portion 24 may be a
cavity of the optical device 20 and may have a cross-section
similar to a mathematical normal distribution (e.g., a Gaussian)
line. The recess portion 24 may be disposed above the light source
10. When a circumference of the recess portion 24 is measured along
a plane that is substantially perpendicular to the optical axis Z,
a first circumference of the recess portion 24, which is proximate
to the light source 10, is greater than a second circumference of
the recess portion 24, which is distant to the light source 10. The
recess portion 24 may be provided above the light source 10 to face
the light source 10 and to cover the light source 10.
[0069] The light incident surface 23 may include a first curved
surface 23a and a second curved surface 23b and may have an
inflection point A at a contact point at which the first curved
surface 23a and the second curved surface 23b contact each other.
The first curved surface 23a may be a concavely curved surface
formed by allowing a center thereof through which the optical axis
Z passes to be recessed concavely toward the second surface 22. In
other words, the first curved surface 23a is concave. The optical
axis Z passes through the center of the first curved surface 23a.
The second curved surface 23b may be a convexly curved surface
extended from an edge of the first curved surface 23a to be
connected to the first surface 21.
[0070] As illustrated in FIG. 2, a transverse cross-section of the
light incident surface 23 may have a bilaterally symmetrical
structure with respect to the optical axis Z. For example, the
first curved surface 23a and the second curved surface 23b may be
symmetrical with respect to the optical axis Z. A vertical
cross-sectional shape of a half of the light incident surface 23
may have an "S" shape.
[0071] FIGS. 3 and 4 are enlarged views illustrating a portion of
the light incident surface 23. FIG. 3 is a cross-sectional view
schematically illustrating an enlarged light incident surface 23 of
the optical device 20 of FIG. 2, according to an exemplary
embodiment of the present inventive concept. FIG. 4 is a
cross-sectional view illustrating a relationship between an angle
of incidence and a refraction angle of the light incident surface
23 of the optical device 20 of FIG. 3, according to an exemplary
embodiment of the present inventive concept.
[0072] As illustrated in FIG. 3, a shape of the light incident
surface 23 may have a structure satisfying the following conditions
1 to 3.
[0073] Condition 1: dR/d.theta.<0 within a range of
0.degree..ltoreq..theta..ltoreq.55.degree..
[0074] Condition 2: dR/d.theta.=0 within a range of
55.degree.<.theta.<65.degree..
[0075] Condition 3: dR/d.theta.>0 within a range of
65.degree..ltoreq..theta..
[0076] For example, when an intersection point between the optical
axis Z and a light emission surface of the light source 10 is
defined as a reference point O, "R" refers to a straight line
connecting the reference point O and an arbitrary point of the
light incident surface 23 to each other, and ".theta." refers to an
angle formed by the straight line "R" with respect to the optical
axis Z.
[0077] Based on the case of .theta.=0.degree., a change in a length
of "R" may be a negative number as .theta. increases within a range
of about .theta..ltoreq.55.degree. and may be a positive number as
.theta. increases within a range of .theta..gtoreq.65.degree.. In
other words, in the range of
0.degree..ltoreq..theta..ltoreq.55.degree., as .theta. increases,
the length of "R" decreases. Thus, dR/d.theta.<0 within a range
of 0.degree..ltoreq..theta..ltoreq.55.degree.. In the range of
65.degree..ltoreq..theta., as .theta. increases, the length of "R"
increases. Thus, dR/d.theta.>0 within the range of
65.degree..ltoreq..theta.. In addition, the light incident surface
23 may have a shape in which a change in the length of "R" does not
occur within a range of 55.degree.<.theta.<65.degree.. In
other words, within the range of
55.degree.<.theta.<65.degree., the length of "R" does not
change as .theta. increases. A gradient of the light incident
surface 23 is reversed within the range of
55.degree.<.theta.<65.degree..
[0078] Further, as illustrated in FIG. 4, a shape of the light
incident surface 23 may have a structure satisfying the following
conditions 4 to 6 together with the conditions 1 to 3, or the shape
of the light incident surface 23 may have a structure satisfying
the following conditions 4 to 6 alone.
[0079] Condition 4: .theta.2/.theta.1>1 within a range of
0.degree..ltoreq..theta.1.ltoreq.55.degree..
[0080] Condition 5: .theta.2/.theta.1=1 within a range of
55.degree.<.theta.1<65.degree..
[0081] Condition 6: .theta.2/.theta.1<1 within a range of
65.degree..ltoreq..theta.1.
[0082] ".theta.1" refers to an angle of incidence of light formed
by arbitrary light L emitted from the light source 10 and incident
on the light incident surface 23, with respect to the optical axis
Z, and ".theta.2" refers a refraction angle of light formed by the
light L having the angle of incidence .theta.1 refracted from the
light incident surface 23 toward the second surface 22, with
respect to the optical axis Z. In other words, when point O falls
along the optical axis Z, the light L emitted from point O has an
angle ".theta.1" with respect to the optical axis Z, and when the
light L enters the optical device 20, the light L refracts to have
an angle ".theta.2" with respect to the optical axis Z.
[0083] Light from the light source 10 may be spread on the light
incident surface 23 within a range of
0.degree..ltoreq..theta.1.ltoreq.55.degree., and be vertically
incident on the light incident surface 23 within a range of
55.degree.<.theta.1<65.degree.. In other words, with the
range of 55.degree.<.theta.1<65.degree., ".theta.1" and
".theta.2" are equal. An optical path of light collected on the
light incident surface 23 may be provided within a range of
65.degree..ltoreq..theta.1. The light incident surface 23 may have
a structure having a cross-section that reverses the direction in
which light L emitted from the light structure 10 is refracted
[0084] FIGS. 5, 6A and 6B schematically illustrate optical paths in
the optical device 20, according to exemplary embodiments of the
present inventive concept. FIG. 5 is a cross-sectional view
schematically illustrating an optical path of light emitted from
the light source 10 of FIG. 2 and passing through the optical
device 20 of FIG. 2, according to an exemplary embodiment of the
present inventive concept. FIG. 6A is a cross-sectional view
schematically illustrating an optical path of light refracted at
the first surface 21 of the optical device 20 of FIG. 2 and emitted
externally, according to an exemplary embodiment of the present
inventive concept. FIG. 6B is a cross-sectional view schematically
illustrating an optical path of light refracted at the first
surface 21 of the optical device 20 of FIG. 2 and emitted
externally, according to an exemplary embodiment of the present
inventive concept.
[0085] As illustrated in FIG. 5, the light incident surface 23 may
be located on a central portion of the first surface 21
corresponding to a bottom surface of the optical device 20, facing
the substrate 30 on which the optical device 20 is mounted,
according to an exemplary embodiment of the present inventive
concept. The light incident surface 23 may have the first curved
surface 23a and the second curved surface 23b connected to each
other through the inflection point A. A vertical cross-sectional
shape of the light incident surface 23 may have an "S" shape. In
the case of the light incident surface 23 described above, light
emitted from the light source 10 at a small angle with respect to
the optical axis Z may be diffused through the light incident
surface 23. In addition, an optical path may be provided on which
light emitted at a large angle with respect to the optical axis Z
is collected inwardly of the optical device 20 in a direction in
which a refraction direction of light is reversed once that the
light enters the optical device 20. For example, light entering the
light incident surface 23 at a first large angle with respect to
the optical axis Z is refracted in a first direction once it enters
the optical device 20. In addition, light entering the same side of
the light incident surface 23 at a second large angle with respect
to the optical axis Z is refracted in a second direction which
crosses the first direction when the light enters the optical
device 20. Thus, unlike a general diffusion lens for only allowing
for a uniform diffusion direction, a section B in which a
refraction direction of light is reversed may be provided. Thus, a
uniformity of brightness distribution in a central region of the
optical device 20 is increased.
[0086] In addition, as illustrated in FIGS. 6A and 6B, since the
first surface 21, which is the bottom surface of the optical device
20, according to an exemplary embodiment of the present inventive
concept, has a convex shape in a manner similar to that of the
second surface 22 corresponding to a light emission surface, a
portion of light, L2, reflected from the second surface 22 of light
L1 emitted from the light source 10, may not be reflected a second
time from the first surface 21, but is refracted to be directly
emitted externally of the optical device 20. Thus, light may be
spread across a wide lateral region. In other words, the first
surface 21 may also function as a light emission surface, and a
distance between the first surface 21 and the substrate 30 on which
the optical device 20 is mounted may be secured, such that
brightness distribution uniformity in a central portion of the
optical device 20 may be increased.
[0087] With reference to FIGS. 7A and 7B, the first surface 21 may
further include a support portion 26 supporting the optical device
20. The support portion 26 may be provided in plural and the
plurality of support portions 26 may be spaced apart from one
another along a circumference of the recess portion 24. The optical
device 20 may be disposed, for example, on the circuit board 30
through the support portion 26.
[0088] The second surface 22 may be disposed to oppose the first
surface 21. The second surface 22 may be provided as a light
emission surface and correspond to an upper surface of the optical
device 20, from which light having entered the interior of the
optical device 20 through the light incident surface 23 is
externally emitted.
[0089] As illustrated in FIG. 2, the second surface 22 may be
shaped as a dome and may extend upwardly from an edge of the first
surface 21 while having a structure in which a central portion of
the structure of the second surface 22 is recessed toward the
recess portion 24 at a location through which the optical axis Z
passes. Thus, the second surface 22 includes a concave portion at a
central portion thereof where the optical axis Z passes through. In
other words, with reference to FIG. 2, the second surface 22 may
have a concave portion 22a being recessed toward the first surface
21 to have a concavely curved surface, and a convex portion 22b
having a convexly curved surface continuously extended from an edge
of the concave portion 22a to an outer edge of the optical device
20.
[0090] On the second surface 22, a plurality of concave-convex
portions 22c may be periodically arranged in a direction from the
optical axis Z to the outer edge of the optical device 20. The
plurality of concave-convex portions 22c may have a ring shaped
structure corresponding to a transverse cross-sectional shape of
the optical device 20, and may form concentric circles with respect
to the optical axis Z. In addition, the plurality of concave-convex
portions 22c may be arranged in a radially diffused form while
forming a periodical pattern along a surface of the second surface
22, based on the optical axis Z.
[0091] The plurality of concave-convex portions 22c may be spaced
apart from one another by a predetermined pitch P to form a
pattern. In this case, the pitch P between the plurality of
concave-convex portions 22c may be within a range of about 0.01 mm
to about 0.04 mm. The plurality of concave-convex portions 22c may
compensate for a difference in performance between the optical
devices 20 due to minute manufacturing errors that may occur in a
process of manufacturing the optical devices 20. Accordingly,
uniformity of brightness distribution may be increased.
[0092] The optical device 20 may be formed using a resin material
having light transmissivity which, for example, may contain
polycarbonate (PC), polymethyl methacrylate (PMMA), an acrylic
resin, or the like. In addition, the optical device 20 may be
formed of glass, but exemplary embodiments of the present inventive
concept are not limited thereto.
[0093] The optical device 20 may contain a light dispersion
material within a range of about 3% to about 15%. The light
dispersion material may include, for example, SiO.sub.2, TiO.sub.2
or Al.sub.2O.sub.3. In a case in which the light dispersion
material is contained in a content of less than 3%, light may not
be sufficiently distributed such that light dispersion effects may
not be expected. In addition, in a case in which the light
dispersion material is contained in a content of more than 15%, an
amount of light emitted outwardly from the optical device 20 may be
reduced. Thus, light extraction efficiency may be reduced.
[0094] The optical device 20 may be formed using a method of
injecting a liquid solvent into a mold to be solidified. For
example, an injection molding method, a transfer molding method, a
compression molding method, or the like, may be used.
[0095] The substrate 30 may be provided as a general flame
retardant 4 (FR4) type printed circuit board (PCB) or a flexible
PCB, and may be formed using an organic resin material containing
epoxy, triagine, silicon rubber, polyimide, or the like, and other
organic resin materials. The substrate 30 may also be formed using
a ceramic material such as silicon nitride, AlN, Al.sub.2O.sub.3 or
the like, or formed using a metal or a metal compound as in a
metal-core printed circuit board (MCPCB), a metal copper clad
laminate (MCCL), or the like.
[0096] FIG. 7A is a cross-sectional view schematically illustrating
a light source module, according to an exemplary embodiment of the
present inventive concept. FIG. 7B is a plan view schematically
illustrating the light source module of FIG. 7A, according to an
exemplary embodiment of the present inventive concept. As
illustrated in FIGS. 7A and 7B, the substrate 30 may have a
rectangular bar type structure having a lengthwise extended form,
but exemplary embodiments of the present inventive concept are not
limited thereto. The substrate 30 may have a variety of structures
corresponding to a structure of a product mounted thereon. For
example, the substrate 30 may also have a circular shaped
structure.
[0097] FIG. 8 is a schematic perspective view illustrating a state
in which a light source 10 and an optical device 20 are mounted on
a substrate 30 of FIG. 7A, according to an exemplary embodiment of
the present inventive concept. As illustrated in FIG. 8, fiducial
marks 31 and a light source mounting region 32 may be provided on
the substrate 30. The fiducial marks 31 and the light source
mounting region 32 may respectively demarcate mounting positions of
the optical device 20 and the light source 10 on the substrate. For
example, a plurality of the fiducial marks 31 may be disposed along
a circumference of each light source mounting region 32 on the
substrate 30.
[0098] The light source 10 may be provided in plurality. The
plurality of light sources 10 may be respectively mounted on the
light source mounting regions 32, and may be arranged in a
lengthwise direction of the substrate 30. In addition, the number
of the optical devices 20 may correspond to the number of the light
sources 10, and the optical devices 20 may be mounted on the
substrate 30 in a structure respectively covering the light sources
10 using the fiducial marks 31 of the respective light source
mounting regions 32.
[0099] With reference to FIGS. 7A and 7B, a connector 40 for
forming a connection between the plurality of light sources 10 and
an external power source may be disposed on the substrate 30. The
connector 40 may be mounted on an end region of the substrate 30.
In addition, a circuit wiring, electrically connected to the light
source 10, may be provided on the substrate 30.
[0100] As the light source 10, LED chips having a variety of
structures or an LED package in which the LED chips are mounted may
be used.
[0101] FIG. 9 is a cross-sectional view schematically illustrating
a light source, according to an exemplary embodiment of the present
inventive concept As illustrated in FIG. 9, the light source 10 may
include, for example, a package structure in which an LED chip 11
is mounted within a package body 12 having a reflective cup 13
therein. In addition, the LED chip 11 may be covered by an
encapsulation part 14 containing phosphor. In the exemplary
embodiment of the present inventive concept, the light source 10
has an LED package form. However, the present inventive concept is
not limited thereto.
[0102] The package body 12 may be provided as a base member in
which the LED chip 11 is mounted on and supported thereby. The
package body 12 may be formed using a white molding compound having
high light reflectivity. The white molding compound of the package
body 12 can increase the amount of light that is emitted externally
of the package body 12 by reflecting the light emitted from the LED
chip 11. Such a white molding compound may include a thermosetting
resin-based material having high heat resistance or a silicon
resin-based material. In addition, a white pigment and a filling
material, a hardener, a mold release agent, an antioxidant, an
adhesion improver, or the like, may be added to the thermoplastic
resin-based material. In addition, the package body 12 may also be
formed using FR4, composite epoxy materials 3 (CEM-3), an epoxy
material, a ceramic material, or the like. The package body 12 may
also be formed using a metal such as aluminum (Al).
[0103] The package body 12 may include a lead frame 15 for an
electrical connection to an external power source. The lead frame
15 may be formed using a material having good electrical
conductivity, for example, a metal such as aluminum, copper, or the
like. When the package body 12 is formed using a metal, an
insulation material may be interposed between the package body 12
and the lead frame 15.
[0104] In the case of the reflective cup 13 provided in the package
body 12, the lead frame 15 may be exposed to a bottom surface of
the reflective cup 13 on which the LED chip 11 is mounted. The LED
chip 11 may be electrically connected to the exposed lead frame
15.
[0105] The reflective cup 13 may have a structure in which an area
of a transverse cross-section of a surface thereof exposed to an
upper part of the package body 12 is greater than that of a bottom
surface of the reflective cup 13. The surface of the reflective cup
13 exposed to the upper part of the package body 12 may be defined
as a light emission surface of the light source 10.
[0106] The LED chip 11 may be sealed by the encapsulation part 14
formed in the reflective cup 13 of the package body 12. The
encapsulation part 14 may contain a wavelength conversion
material.
[0107] The wavelength conversion material may include, for example,
one or more phosphors which are excited by light generated by the
LED chip 11. The excited one or more phosphors emit light having a
different wavelength than the wavelength of the light emitted by
the LED chip 11. The encapsulation part 14 may also include the
wavelength conversion material so that light having various colors
as well as white light may be emitted through control of the light
emitted by the LED chip 11.
[0108] For example, when the LED chip 11 emits blue light, white
light may be emitted through a combination of yellow, green, red
and/or orange phosphors included in the wavelength conversion
material. In addition, an LED chip 11 emitting violet, blue, green,
red or infrared light may be included in the light source 10. In
this case, the LED chip 11 may perform controlling of the light so
that a color rendering index (CRI) of emitted light may be
controlled to be within a range of about 40 to about 100. In
addition, the LED chip 11 may emit various types of white light
having a color temperature of about 2000K to about 20000K. In
addition, color may be adjusted to be appropriate for an ambient
atmosphere or for people's moods by generating visible violet,
blue, green, red or orange light as well as infrared light, as
needed. Further, light within a special wavelength band, capable of
promoting growth of plants, may also be generated.
[0109] FIG. 10 illustrates a CIE 1931 chromaticity coordinates
system for illustrating a wavelength conversion material employable
in an exemplary embodiment of the present inventive concept. White
light obtained by combining yellow, green, and red phosphors,
and/or green, red, and blue LED chips may have two or more peak
wavelengths. Referring to FIG. 10, coordinates in format (x, y)
including (0.4476, 0.4074), (0.3484, 0.3516), (0.3101, 0.3162),
(0.3128, 0.3292), and (0.3333, 0.3333) are located in line segments
connected to one another on the CIE 1931 chromaticity coordinates
system. Alternatively, the coordinates (x, y) may be located in a
region surrounded by the line segments and black body radiation
spectrum. A color temperature of the white light may be within a
range of about 2000K to about 20000K.
[0110] Phosphors may be represented by the following empirical
formulae and have a color as described below.
[0111] Oxide-based Phosphors: Yellow and green
Y.sub.3Al.sub.5O.sub.12:Ce, Tb.sub.3Al.sub.5O.sub.12:Ce,
Lu.sub.3Al.sub.5O.sub.12:Ce.
[0112] Silicate-based Phosphors: Yellow and green
(Ba,Sr).sub.2SiO.sub.4:Eu, Yellow and yellowish-orange
(Ba,Sr).sub.3SiO.sub.5:Ce.
[0113] Nitride-based Phosphors: Green .beta.-SiAlON:Eu, yellow
La.sub.3Si.sub.6N.sub.11:Ce, yellowish-orange .alpha.-SiAlON:Eu,
red CaAlSiN.sub.3:Eu, Sr.sub.2Si.sub.5N.sub.8:Eu,
SrSiAl.sub.4N.sub.7:Eu, SrLiAl.sub.3N.sub.4:Eu,
Ln.sub.4-x(Eu.sub.zM.sub.1-z).sub.xSi.sub.12-yAl.sub.yO.sub.3+x+yN.sub.18-
-x-y (0.5.ltoreq.x.ltoreq.3, 0<z<0.3, 0<y.ltoreq.4) (e.g
Ln is a group IIIa element or a rare-earth element, and M is Ca,
Ba, Sr or Mg).
[0114] Fluoride-based Phosphors: KSF-based red
K.sub.2SiF.sub.6:Mn.sub.4+, K.sub.2TiF.sub.6:Mn.sub.4+,
NaYF.sub.4:Mn.sub.4+, NaGdF.sub.4:Mn.sub.4+.
[0115] A composition of phosphors should conform to stoichiometry,
and respective elements may be substituted with other elements in
respective groups of the periodic table of elements. For example,
Sr may be substituted with Ba, Ca, Mg, or the like, of an alkaline
earth group II, and Y may be substituted with lanthanum-based Tb,
Lu, Sc, Gd, or the like. In addition, Eu or the like, an activator,
may be substituted with Ce, Tb, Pr, Er, Yb, or the like, according
to a required level of energy. Further, an activator alone, or a
sub-activator or the like, may be used for modification of
characteristics thereof.
[0116] In the case of a fluoride-based red phosphor, to increase
reliability of the fluoride-based red phosphor under conditions of
high temperature and high humidity, phosphors may be coated with a
fluoride not containing Mn. In addition, a phosphor surface or a
fluoride-coated surface of phosphors that is coated with fluoride
not containing Mn may further be coated with an organic material.
In the case of the fluoride-based red phosphor as described above,
a narrow full width at half maximum of 40 nm or less may be
obtained, unlike in the case of other phosphors. The fluoride-based
red phosphors may be used in high-resolution television (TV) sets
such as ultra-high-definition (UHD) TVs.
[0117] In the wavelength conversion material, a material such as a
quantum dot (QD) may be used to substitute phosphor. In addition, a
mixture of a phosphor and QD may be used in the wavelength
conversion material.
[0118] FIG. 11 is a schematic diagram illustrating a
cross-sectional structure of a QD, according to an exemplary
embodiment of the present inventive concept. The QD may have a
core-shell structure using a group III-V or group II-VI compound
semiconductor. For example, the QD may have a core formed using
CdSe, InP, or the like, and a shell formed using ZnS, ZnSe, or the
like. Further, the QD may have a ligand for stabilization of the
core and the shell. For example, the core may have a diameter
ranging from approximately 1 nm to approximately 30 nm. In an
exemplary embodiment of the present inventive concept, the core may
have a diameter ranging from approximately 3 nm to approximately 10
nm. The shell may have a thickness ranging from approximately 0.1
nm to approximately 20 nm.
[0119] The QD may have various colors depending on the size
thereof. In a case in which the QD is used as a phosphor
substitute, the Qd may be used as a red or green phosphor. When
using the QD, a narrow full width at half maximum of, for example,
about 35 nm, may be obtained.
[0120] In the exemplary embodiment of the present inventive
concept, the wavelength conversion material is included in the
encapsulation part 14. However, the present inventive concept is
not limited thereto. For example, the wavelength conversion
material may be included in a film. The film including the
wavelength conversion material may be attached to a surface of the
LED chip 11. In this case, the application of the wavelength
conversion material having a uniform thickness may be
facilitated.
[0121] FIG. 12 is a cross-sectional view illustrating an LED chip
used as a light source, according to an exemplary embodiment of the
present inventive concept. With reference to FIGS. 12 to 15,
various LED chips used as light sources will be described,
according to exemplary embodiments of the present inventive
concept.
[0122] With reference to FIG. 12, an LED chip 100 may include a
growth substrate 111, a first conductivity-type semiconductor layer
114, an active layer 115, and a second conductivity-type
semiconductor layer 116, sequentially stacked on the growth
substrate 111. A buffer layer 112 may be disposed between the
growth substrate 111 and the first conductivity-type semiconductor
layer 114.
[0123] The growth substrate 111 may be provided as an insulating
substrate such as a sapphire substrate, but the present inventive
concept is not limited thereto. In addition, the growth substrate
111 may be provided as a conductive or semiconductor substrate. For
example, the growth substrate 111 may be formed using SiC, Si,
MgAl.sub.2O.sub.4, MgO, LiAlO.sub.2, LiGaO.sub.2, or GaN as well as
sapphire.
[0124] The buffer layer 112 may be formed of
In.sub.xAl.sub.yGa.sub.1-x-yN (0.ltoreq.x.ltoreq.1,
0.ltoreq.y.ltoreq.1, 0.ltoreq.x+y.ltoreq.1). For example, the
buffer layer 112 may be formed using GaN, AlN, AlGaN, or InGaN. The
buffer layer 112 may be formed by combining a plurality of layers
or gradually changing a composition as required.
[0125] The first conductivity-type semiconductor layer 114 may be
provided as a nitride semiconductor being an n-type semiconductor
In.sub.xAl.sub.yGa.sub.1-x-yN (0.ltoreq.x<1, 0.ltoreq.y<1,
0.ltoreq.x+y<1), and an n-type impurity of the n-type
semiconductor may be silicon (Si). For example, the first
conductivity-type semiconductor layer 114 may contain an n-type GaN
layer.
[0126] According to the exemplary embodiment of the present
inventive concept, the first conductivity-type semiconductor layer
114 may include a first conductivity-type semiconductor contact
layer 114a and a current diffusion layer 114b. An impurity
concentration of the first conductivity-type semiconductor contact
layer 114a may be within a range of about 2.times.10.sup.18
cm.sup.-3 to about 9.times.10.sup.19 cm.sup.-3. A thickness of the
first conductivity-type semiconductor contact layer 114a may be
within a range of about 1 .mu.m to about 5 .mu.m. The current
diffusion layer 114b may have a structure in which a plurality of
In.sub.xAl.sub.yGa.sub.(1-x-y)N (0.ltoreq.x, y.ltoreq.1,
0.ltoreq.x+y.ltoreq.1) layers having different compositions or
different impurity contents are repeatedly stacked. For example,
the current diffusion layer 114b may be an n-type super-lattice
layer having a structure in which an n-type GaN layer having a
thickness of about 1 nm to about 500 nm and/or two or more layers
formed of Al.sub.xIn.sub.yGa.sub.zN (0.ltoreq.x,y,z.ltoreq.1,
except for x=y=z=0) and having different compositions are
repeatedly stacked. An impurity concentration of the current
diffusion layer 114b may be approximately 2.times.10.sup.18
cm.sup.3 to approximately 9.times.10.sup.19 cm.sup.3. The current
diffusion layer 114b may further include an insulation material
layer as needed.
[0127] The second conductivity-type semiconductor layer 116 may be
provided as a nitride semiconductor layer being a p-type
semiconductor In.sub.xAl.sub.yGa.sub.1-x-yN (0.ltoreq.x<1,
0.ltoreq.y<1, 0.ltoreq.x+y<1), and a p-type impurity of the
p-type semiconductor may be Mg. For example, the second
conductivity-type semiconductor layer 116 may have a single layer
structure, or a multilayer structure having different compositions
as illustrated in the exemplary embodiment of the present inventive
concept. As illustrated in FIG. 12, the second conductivity-type
semiconductor layer 116 may include an electron blocking layer
(EBL) 116a, a low concentration p-type GaN layer 116b, and a high
concentration p-type GaN layer 116c provided as a contact layer.
For example, the EBL 116a may have a structure in which a plurality
of In.sub.xAl.sub.yGa.sub.(1-x-y)N (0.ltoreq.x.ltoreq.1,
0.ltoreq.y.ltoreq.1, 0.ltoreq.x+y.ltoreq.1) layers having different
compositions and having a thickness within a range of about 5 nm to
about 100 nm are stacked, or may have a single layer formed of
Al.sub.yGa.sub.(1-y)N (0<y.ltoreq.1). An energy band gap of the
EBL 116a may be reduced in a direction away from an active layer
115. For example, a composition of A1 of the EBL 116a may be
reduced in a direction away from the active layer 115.
[0128] The active layer 115 may have a multiple quantum well (MQW)
structure in which a quantum well layer and a quantum barrier layer
are alternately stacked. For example, the quantum well layer and
the quantum barrier layer may be In.sub.xAl.sub.yGa.sub.1-x-yN
(0.ltoreq.x.ltoreq.1, 0.ltoreq.y.ltoreq.1, 0.ltoreq.x+y.ltoreq.1)
layers having different compositions. For example, the quantum well
layer may be an In.sub.xGa.sub.1-xN (0<x.ltoreq.1) layer, and
the quantum barrier layer may be a GaN or AlGaN layer. Thicknesses
of the quantum well layer and the quantum barrier layer may be
respectively within a range of about 1 nm to about 50 nm. The
active layer 115 is not limited to an MQW structure, but may have a
single quantum well (SQW) structure.
[0129] The LED chip 100 may include a first electrode 119a disposed
on the first conductivity-type semiconductor layer 114, and an
ohmic contact layer 118 and a second electrode 119b sequentially
disposed on the second conductivity-type semiconductor layer
116.
[0130] The first electrode 119a may contain a material such as Ag,
Ni, Al, Cr, Rh, Pd, Ir, Ru, Mg, Zn, Pt, Au, and the like, but the
present inventive concept is not limited thereto. The first
electrode 119a may be formed in a single layer or in a two or more
layer structure. A pad electrode layer may be further provided on
the first electrode 119a. The pad electrode layer may be a layer
containing Au, Ni, Sn, or the like.
[0131] The ohmic contact layer 118 may be implemented in a variety
of methods depending on a chip structure. For example, in the case
of a flip-chip structure, the ohmic contact layer 118 may contain a
metal such as Ag, Au, Al, or the like, and a transparent conductive
oxide such as indium tin oxide (ITO), zinc indium oxide (ZIO),
gallium indium oxide (GIO), or the like. In the case of an opposite
layout structure of the flip-chip structure, the ohmic contact
layer 118 may be configured as a light transmitting electrode. The
light transmitting electrode may be provided as a transparent
conductive oxide layer or nitride layer. For example, the light
transmitting electrode may include ITO, zinc-doped indium tin oxide
(ZITO), ZIO, GIO, zinc tin oxide (ZTO), fluorine-doped tin oxide
(FTO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide
(GZO), In.sub.4Sn.sub.3O.sub.12, or Zn.sub.(1-x)Mg.sub.xO (Zinc
Magnesium Oxide, 0.ltoreq.x.ltoreq.1). The ohmic contact layer 118
may also contain graphene, as necessary. The second electrode 119b
may contain Al, Au, Cr, Ni, Ti, or Sn.
[0132] FIG. 13A is a plan view illustrating an LED chip used as a
light source, according to an exemplary embodiment of the present
inventive concept. FIG. 13B is a side cross-sectional view of the
LED chip of FIG. 13A, taken along line I-I' of FIG. 13A, according
to an exemplary embodiment of the present inventive concept.
[0133] An LED chip 200 illustrated in FIGS. 13A and 13B may have a
large area structure for high output illumination. The LED chip 200
may have a structure for an increase in current dispersion
efficiency and heat dissipation efficiency.
[0134] The LED chip 200 may include a light emitting laminate S, a
first electrode 220, an insulating layer 230, a second electrode
208, and a conductive substrate 210. The light emitting laminate S
may include a first conductivity-type semiconductor layer 204, an
active layer 205, and a second conductivity-type semiconductor
layer 206 stacked sequentially.
[0135] The first electrode 220 may include one or more conductive
vias 280 electrically insulated from the second conductivity-type
semiconductor layer 206 and the active layer 205 and extended to at
least a portion of a region of the first conductivity-type
semiconductor layer 204 to be electrically connected to the first
conductivity-type semiconductor layer 204. The conductive vias 280
may be extended from an interface of the first electrode 220 to an
interior of the first conductivity-type semiconductor layer 204
while penetrating through the second electrode 208, the second
conductivity-type semiconductor layer 206, and the active layer
205. The conductive vias 280 may be formed through an etching
process, for example, inductively coupled plasma reactive ion
etching (ICP-RIE), or the like.
[0136] On the first electrode 220, the insulating layer 230 for
electrically insulating regions except for the conductive substrate
210 and the first conductivity-type semiconductor layer 204 from
the first electrode 220 may be provided. As illustrated in FIG.
13B, the insulating layer 230 may be formed on side surfaces of the
conductive vias 280 as well as between the second electrode 208 and
the first electrode 220. Thus, the second electrode 208, the second
conductivity-type semiconductor layer 206, and the active layer 205
exposed to the side surfaces of the conductive vias 280 may be
insulated from the first electrode 220. The insulating layer 230
may be formed by depositing an insulation material such as
SiO.sub.2, SiO.sub.xN.sub.y, or Si.sub.xN.sub.y.
[0137] A contact region C of the first conductivity-type
semiconductor layer 204 may be exposed through the conductive vias
280, and a portion of the first electrode 220 may contact the
contact region C through the conductive vias 280. Thus, the first
electrode 220 may be connected to the first conductivity-type
semiconductor layer 204.
[0138] The number, shape, or pitch of the conductive vias 280, or a
contact diameter or a contact area of the conductive vias 280 with
the first and second conductivity-type semiconductor layers 204 and
206, may be designed to reduce contact resistance. The conductive
vias 280 may be formed to be arranged in rows and columns in
various forms to increase current flow. A contact area and the
number of the conductive vias 280 may be adjusted such that the
area of the contact region C may be within a range of about 0.1% to
about 20% of a planar area of the light emitting laminate S.
According to an exemplary embodiment of the present inventive
concept, the area of the contact region C may be within a range of
about 0.5% to about 15% of a planar area of the light emitting
laminate S. According to an exemplary embodiment of the present
inventive concept, the area of the contact region C may be within a
range of about 1% to about 10% of the planar area of the light
emitting laminate S. In a case in which the area of the contact
region C is smaller than 0.1% of a planar area of the light
emitting laminate S, current dispersion may not be uniform. Thus
light emission characteristics of the LED chip 200 may be reduced.
In a case in which the area of the contact region C is 20% or more
of the planar area of the light emitting laminate S, light emission
characteristics and brightness of the light emitted from the LED
chip 200 may be reduced since a light emission area of the light
emitting laminate S is small.
[0139] A radius of the conductive vias 280 in a contact region
thereof with the first conductivity-type semiconductor layer 204
may be within a range of, for example, about 1 .mu.m to about 50
.mu.m, and the number of the conductive vias 280 may be 1 to 48000
for each light emitting laminate S region, depending on an area of
the light emitting laminate S region. Although the number of the
conductive vias 280 is changed according to the area of the light
emitting laminate S region, for example, 2 to 45000 conductive vias
280 may be disposed in a light emitting laminate S region. In an
exemplary embodiment of the present inventive concept, 5 to 40000
conductive vias 280 may be disposed in a light emitting laminate S
region. In an exemplary embodiment of the present inventive
concept, 10 to 35000 conductive vias 280 may be disposed in a light
emitting laminate S region. A distance between the conductive vias
280 may be within a range of about 10 .mu.m to about 1000 .mu.m in
a matrix structure having rows and columns. In an exemplary
embodiment of the present inventive concept, a distance between the
conductive vias 280 may be within a range of about 50 .mu.m to
about 700 .mu.m. In an exemplary embodiment of the present
inventive concept, a distance between conductive vias 280 may be
within a range of about 100 .mu.m to about 500 .mu.m. In an
exemplary embodiment of the present inventive concept, a distance
between conductive vias 280 may be within a range of 150 .mu.m to
400 .mu.m.
[0140] In a case in which a distance between the conductive vias
280 is less than 10 .mu.m, the number of conductive vias 280 per
unit area of the light emitting laminate S may increase, and a
light emission area of the light emitting laminate S may be
reduced. Thus, light emission efficiency of the LED chip 200 may be
reduced. In a case in which a distance between the conductive vias
280 is greater than 1000 .mu.m, current may not be evenly diffused.
Thus light emission efficiency of the LED chip 200 may be reduced.
A depth of the conductive vias 280 may be changed depending on
thicknesses of the second conductivity-type semiconductor layer 206
and the active layer 205, and for example, the depth of the
conductive vias 280 may be within a range of about 0.1 .mu.m to
about 5.0 .mu.m.
[0141] The second electrode 208 may provide an electrode formation
region E extended outwardly of the light emitting laminate S to be
exposed externally as illustrated in FIG. 13B. The electrode
formation region E may include an electrode pad portion 219
connecting the second electrode 208 to an external power source.
Although the electrode formation region E has been illustrated as
being a single region, a plurality of electrode formation regions E
may be provided in the second electrode 208 as needed. The
electrode formation region E may be formed in a corner of the LED
chip 200 to increase a light emission area as illustrated in FIG.
13A.
[0142] In the exemplary embodiment of the present inventive
concept, an etching stop insulating layer 240 may be disposed
around an electrode pad portion 219. The etching stop insulating
layer 240 may be formed in the electrode formation region E after
the light emitting laminate S is formed and before the second
electrode 208 is formed, and may serve as an etching stop portion
at the time of performing an etching process to form the electrode
formation region E.
[0143] The second electrode 208 may include a material having a
high level of reflectivity. The second electrode 208 may form an
ohmic contact with the second conductivity-type semiconductor layer
206. The second electrode 208 may include the reflective material
included in the second electrode 208.
[0144] FIG. 14 is a side cross-sectional view illustrating an LED
chip used as a light source, according to an exemplary embodiment
of the present inventive concept.
[0145] With reference to FIG. 14, an LED chip 300 may include a
semiconductor laminate 310 formed on a substrate 301. The
semiconductor laminate 310 may include a first conductivity-type
semiconductor layer 314, an active layer 315, and a second
conductivity-type semiconductor layer 316.
[0146] The LED chip 300 may include first and second electrodes 322
and 324 respectively connected to the first and second
conductivity-type semiconductor layers 314 and 316. The first
electrode 322 may include connection electrode portions 322a that
may be conductive vias penetrating the second conductivity-type
semiconductor layer 316 and the active layer 315 to be connected to
the first conductivity-type semiconductor layer 314, and a first
electrode pad 322b connected to the connection electrode portions
322a. The connection electrode portions 322a may be surrounded by
an insulating portion 321 to be electrically isolated from the
active layer 315 and the second conductivity-type semiconductor
layer 316. In the LED chip 300, the connection electrode portions
322a may be formed in a region in which the semiconductor laminate
310 has been etched. The number, a shape, or a pitch of the
connection electrode portions 322a, or a contact area thereof with
the first conductivity-type semiconductor layer 314 may be designed
to reduce contact resistance. In addition, the connection electrode
portions 322a may be arranged so that rows and columns thereof may
be formed on the semiconductor laminate 310, thereby increasing
current flow. The second electrode 324 may include an ohmic contact
layer 324a formed on the second conductivity-type semiconductor
layer 316, and a second electrode pad 324b.
[0147] The connection electrode portions and the ohmic contact
layers 322a and 324a may respectively have a structure in which a
conductive material having an ohmic characteristic with the first
and second conductivity-type semiconductor layers 314 and 316 is
formed in a single layer or a multilayer structure. For example,
the connection electrode portions and the ohmic contact layers 322a
and 324a may be formed in a process of depositing or sputtering one
or more materials such as Ag, Al, Ni, Cr, a transparent conductive
oxide (TCO), and the like.
[0148] The first and second electrode pads 322b and 324b may be
connected to the connection electrode portions and the ohmic
contact layers 322a and 324a, respectively, so as to function as
external terminals of the LED chip 300. For example, the first and
second electrode pads 322b and 324b may be formed using Au, Ag, Al,
Ti, W, Cu, Sn, Ni, Pt, Cr, NiSn, TiW, AuSn, or a eutectic metal
thereof.
[0149] The first and second electrodes 322 and 324 may be disposed
in a single direction and mounted on a lead frame, or the like, in
a flip-chip form.
[0150] The first and second electrodes 322 and 324 may be
electrically isolated from each other by the insulating portion
321. In an exemplary embodiment of the present inventive concept,
the insulating portion 321 may include any material having an
electrical insulation property. In an exemplary embodiment of the
present inventive concept, the insulating portion 321 may include a
material having a low light absorption rate. For example, the
insulating portion 321 may include a silicon oxide and a silicon
nitride such as SiO.sub.2, SiO.sub.xN.sub.y, Si.sub.xN.sub.y, or
the like. The insulating portion 321 may have a light reflective
structure formed by dispersing a light reflective filler in a light
transmitting material as needed. In addition, the insulating
portion 321 may have a multilayer reflective structure in which a
plurality of insulating films having different refractive indices
are alternately stacked. For example, the multilayer reflective
structure may be implemented by a distributed Bragg reflector in
which a first insulating film having a first refractive index and a
second insulating film having a second refractive index are
alternately stacked.
[0151] In an exemplary embodiment of the present inventive concept,
the multilayer reflective structure may include 2 to 100 insulating
films having different refractive indices stacked on each other. In
an exemplary embodiment of the present inventive concept, the
multilayer reflective structure may include 3 to 70 insulating
films having different refractive indices stacked on each other. In
an exemplary embodiment of the present inventive concept, the
multilayer reflective structure may include 4 to 50 insulating
films having different refractive indices stacked on each other.
The plurality of insulating films having the multilayer reflective
structure may be respectively formed using oxide or nitride such as
SiO.sub.2, SiN, SiO.sub.xN.sub.y, TiO.sub.2, Si.sub.3N.sub.4,
Al.sub.2O.sub.3, TiN, AlN, ZrO.sub.2, TiAlN, TiSiN, or the like, or
through a combination thereof. For example, when a wavelength of
light generated by the active layer is defined as "k" and "n" is
defined as a refractive index of a corresponding layer, the first
and second insulating films may be formed to have a thickness of
.lamda./4n, and may have a thickness of approximately 300 .ANG. to
900 .ANG.. In this case, a refractive index and a thickness of the
first and second insulating films may be designed such that the
multilayer reflective structure may have a high degree of
reflectivity (e.g., 95% or higher) with respect to a wavelength of
light generated by the active layer 315.
[0152] The refractive index of the first insulating film and
refractive index of the second insulating film may respectively be
in a range of around 1.4 to around 2.5, and may respectively have
values less than refractive indices of the first conductivity-type
semiconductor layer 314 and the substrate 301. In addition, the
refractive index of the first insulating film and refractive index
of the second insulating film may respectively have values less
than the refractive index of the first conductivity-type
semiconductor layer 314 but greater than the refractive index of
the substrate 301.
[0153] FIG. 15 is a schematic perspective view and a
cross-sectional view illustrating an LED chip, according to an
exemplary embodiment of the present inventive concept.
[0154] With reference to FIG. 15, an LED chip 400 may include a
base layer 412 formed of a first conductivity-type semiconductor
material and a plurality of light emitting nanostructures 410
disposed thereon.
[0155] The LED chip 400 may include a substrate 411 having an upper
surface on which the base layer 412 is disposed. Concave-convex
portions G may be formed on the upper surface of the substrate 411.
The concave-convex portions G may increase the quality of a grown
single crystal as well as increase light extraction efficiency. The
substrate 411 may be provided as an insulating substrate, a
conductive substrate, or a semiconductor substrate. For example,
the substrate 411 may be formed using sapphire, SiC, Si,
MgAl.sub.2O.sub.4, MgO, LiAlO.sub.2, LiGaO.sub.2, or GaN.
[0156] The base layer 412 may include a first conductivity-type
nitride semiconductor layer and may provide a growth surface of the
light emitting nanostructure 410. The base layer 412 may be
provided as a nitride semiconductor satisfying
In.sub.xAl.sub.yGa.sub.1-x-yN (0.ltoreq.x<1, 0.ltoreq.y<1,
0.ltoreq.x+y<1) and may be doped with an n-type impurity such as
Si. For example, the base layer 412 may be formed using n-type
GaN.
[0157] An insulating film 413 having openings for growth of the
light emitting nanostructures 410. Nanocores 404 of the light
emitting nanostructures 410 may be formed on the base layer 412.
The nanocores 404 may be formed on a region of the base layer 412
exposed through the openings of insulating film 413. The insulating
film 413 may be used as a mask allowing for the growth of the
nanocores 404. For example, the insulating film 413 may be formed
of an insulation material such as SiO.sub.2 or SiN.sub.x.
[0158] The light emitting nanostructure 410 may include a main
portion M having a hexagonal prism shaped structure and an upper
end portion T disposed on the main portion M. The main portion M of
the light emitting nanostructure 410 may have lateral surfaces
having the same crystalline surface, and the upper end portion T of
the light emitting nanostructure 410 may have a crystalline surface
different from those of the lateral surfaces of the main portion M
of the light emitting nanostructure 410. The upper end portion T of
the light emitting nanostructure 410 may have a hexagonal pyramid
shape. Such a structural shape may be determined by the nanocore
404. The nanocore 404 may also be divided into the main portion M
and the upper end portion T.
[0159] The light emitting nano structure 410 may include the
nanocore 404 configured as a first conductivity-type nitride
semiconductor. An active layer 405 and a second conductivity-type
nitride semiconductor layer 406 sequentially disposed on a surface
of the nanocore 404.
[0160] The LED chip 400 may include a contact electrode 416
connected to the second conductivity-type nitride semiconductor
layer 406. The contact electrode 416 employed in the exemplary
embodiment of the present inventive concept may be formed using a
conductive material having light transmission properties. The
contact electrode 416 may cause the light emitting nanostructures
410 to emit light, for example, in a direction opposite to the
substrate. The contact electrode 416 may include a transparent
conductive oxide layer or a nitride layer. For example, the contact
electrode 416 may be formed using ITO, ZITO, ZIO, GIO, ZTO, FTO,
AZO, GZO, In.sub.4Sn.sub.3O.sub.12, or Zn.sub.(1-x)Mg.sub.xO (Zinc
Magnesium Oxide, 0.ltoreq.x.ltoreq.1). In addition, the contact
electrode 416 may contain graphene, as needed.
[0161] The contact electrode 416 is not limited to a light
transmitting material. The contact electrode 416 may include a
reflective electrode structure, as needed. For example, the contact
electrode 416 may contain a material such as Ag, Ni, Al, Rh, Pd,
Ir, Ru, Mg, Zn, Pt, Au, or the like, and may employ a two or more
layer structure such as Ni/Ag, Zn/Ag, Ni/Al, Zn/Al, Pd/Ag, Pd/Al,
Ir/Ag, Ir/Au, Pt/Ag, Pt/Al, Ni/Ag/Pt, or the like. A flip-chip
structure may be implemented by employing the reflective electrode
structure as described above.
[0162] An insulating protective layer 418 may be formed on the
light emitting nanostructures 410. The insulating protective layer
418 may be a passivation portion protecting the light emitting
nanostructures 410. In addition, the insulating protective layer
418 may be formed of a material having light transmission
properties so that light generated in the light emitting
nanostructures 410 may be extracted. In this case, the insulating
protective layer 418 may be formed by selectively using a material
having appropriate refractivity to increase light extraction
efficiency.
[0163] In the exemplary embodiment of the present inventive
concept, after the contact electrode 416 is formed, the insulating
protective layer 418 may fill a space between the plurality of
light emitting nanostructures 410. As a material of the insulating
protective layer 418, an insulation material such as SiO.sub.2 or
SiN.sub.x may be used. The insulating protective layer 418 may
include a material such as TetraEthylOrthoSilane (TEOS),
BoroPhospho Silicate Glass (BPSG), CVD-SiO.sub.2, Spin-on Glass
(SOG), or Spin-on Dielectric (SOD).
[0164] The insulating protective layer 418 may be used to fill a
space between the light emitting nanostructures 410, but the
present inventive concept is not limited thereto. For example, a
space between the light emitting nanostructures 410 may also be
filled with an electrode element such as an element of the contact
electrode 416. In addition, the space between the light emitting
nanostructures 410 may be filled with a reflective electrode
material described above.
[0165] The LED chip 400 may include first and second electrodes
419a and 419b. The first electrode 419a may be disposed in a
portion of a partially exposed region of the base layer 412. The
base layer 412 includes a first conductivity-type semiconductor.
The second electrode 419b may be disposed in an exposed region of
the contact electrode 416. The arrangement of the first and second
electrodes 419a and 419b is not limited to the illustration above
described with reference to FIG. 15. The first and second
electrodes 419a and 419b may be variously arranged depending on the
use of the LED chip 400.
[0166] The LED chip 400 may have a core-shell nanostructure, and
may have low heat generation due to a low combination density, and
may have an increased light emission area through the nanostructure
to thus increase light emission efficiency. In addition, since the
LED chip 400 may include a non-polar active layer, a reduction in
light emission efficiency due to polarization may be prevented, and
droop may be controlled.
[0167] In addition, the plurality of the light emitting
nanostructures 410 may emit light having two or more different
wavelengths by having a mask layer with a plurality of open regions
having different diameters, different intervals (e.g., pitches)
between the plurality of open regions of the mask layer, or a
different doping concentration or a different indium (In) content
mixed in the active layer 405 of the light emitting nanostructure.
Thus, white light may be obtained even without using a phosphor in
a single light emitting device by controlling light having
different wavelengths. In addition, light having desired various
colors or white light having different color temperatures may be
obtained by combining the lighting device with a different LED chip
or with a wavelength conversion material such as a phosphor.
[0168] Hereinafter, a lighting device in which a light source
module is employed will be described with reference to FIGS. 16 to
18, according to various exemplary embodiments of the present
inventive concept.
[0169] FIG. 16 is a schematic cross-sectional view of a lighting
device, according to an exemplary embodiment of the present
inventive concept. With reference to FIG. 16, a lighting device
1000 may have a surface light source type structure, for example,
and may be provided as a direct-type backlight unit.
[0170] The lighting device 1000 may include an optical sheet 1040
and a light source module 1010 arranged below the optical sheet
1040.
[0171] The optical sheet 1040 may include a light diffusion sheet
1041, a prism sheet 1042, and a protective sheet 1043.
[0172] The light source module 1010 may include a PCB 1011, a
plurality of light sources 1012 mounted on an upper surface of the
PCB 1011, and a plurality of optical devices 1013 respectively
disposed above the plurality of light sources 1012. The light
source module 1010, according to the exemplary embodiment of the
present inventive concept, may have a structure similar to that of
the light source module 1 of FIG. 1. The plurality of optical
devices 1013 may have a biconvex lens structure. Since a vertical
cross section of a light incident surface has an "S" shape,
uniformity of brightness distribution on a central portion of the
optical devices 1013 may be increased. A detailed description of
the respective constituent elements of the light source module 1010
can be understood with reference to the foregoing exemplary
embodiments of the present inventive concept, for example, with
reference to the exemplary embodiment of the present inventive
concept described with reference to FIG. 7.
[0173] FIG. 17 is a schematic exploded perspective view of a
bulb-type lighting device, according to an exemplary embodiment of
the present inventive concept.
[0174] A lighting device 1100 may include a socket 1110, a power
supply unit 1120, a heat radiating unit 1130, a light source module
1140, and an optical unit 1150.
[0175] According to an exemplary embodiment of the present
inventive concept, the light source module 1140 may include a light
emitting device array, and the power supply unit 1120 may include a
light emitting device driving unit.
[0176] The socket 1110 may be configured such that it may be
mounted on an existing lighting apparatus. Power supplied to the
lighting device 1100 may be applied through the socket 1110. As
illustrated, the power supply unit 1120 may include a first power
supply portion 1121 and a second power supply portion 1122
separated from and coupled to each other. The heat radiating unit
1130 may include an internal heat radiating portion 1131 and an
external heat radiating portion 1132. The internal heat radiating
portion 1131 may be directly connected to the light source module
1140 and/or to the power supply unit 1120. Heat may be transferred
to the external heat radiating portion 1132 by the internal heat
radiating portion 1131. The optical unit 1150 may include an
internal optical portion and an external optical portion, and may
be configured such that light emitted from the light source module
1140 may be uniformly dispersed.
[0177] The light source module 1140 may receive power from the
power supply unit 1120 and emit light to the optical unit 1150. The
light source module 1140 may include one or more light sources 1141
having an optical device, a circuit board 1142, and a controller
1143. The controller 1143 may store driving information of the
light sources 1141 therein.
[0178] The light source module 1140, according to the exemplary
embodiment of the present inventive concept, may have a structure
similar to that of the light source module 1 of FIG. 1. The optical
devices respectively disposed on the light sources 1141 may have a
biconvex lens structure. Since a vertical cross section of a light
incident surface of the optical devices has an "S" shape,
uniformity of brightness distribution on a central portion thereof
may be increased. A detailed description of the respective
constituent elements of the light source module 1140 can be
understood with reference to the foregoing exemplary embodiments of
the present inventive concept, for example, with reference to the
exemplary embodiment of the present inventive concept with
reference to FIG. 7.
[0179] FIG. 18 is a schematic exploded perspective view of a bar
type lighting device, according to an exemplary embodiment of the
present inventive concept.
[0180] A lighting device 1200 may include a heat radiating member
1210, a cover 1220, a light source module 1230, a first socket
1240, and a second socket 1250. A plurality of heat radiating fins
1211 and 1212 having a concave-convex surface shape may be formed
on an inner surface or/and an external surface of the heat
radiating member 1210. The heat radiating fins 1211 and 1212 may be
designed to have various forms and intervals therebetween. A
support portion 1213 having a protruding form may be formed
inwardly of the heat radiating member 1210. The light source module
1230 may be fixed to the support portion 1213. A stop protrusion
1214 may be formed on both ends of the heat radiating member
1210.
[0181] The cover 1220 may include a stop groove 1221 formed
therein. The stop groove 1221 may be coupled to the stop protrusion
1214 of the heat radiating member 1210 in a hook coupling
structure. The positions in which the stop groove 1221 and the stop
protrusion 1214 are formed may be changed inversely.
[0182] The light source module 1230 may include a light source
array. The light source module 1230 may include a PCB 1231, a light
source 1232 having an optical device, and a controller 1233. In an
exemplary embodiment of the present inventive concept, the light
source module 1230 includes a plurality of light source 1232. Each
of the light sources 1232 includes an optical device disposed
thereon. As described above, the controller 1233 may store driving
information of the light sources 1232 therein. The PCB 1231 may
include circuit wirings formed therein for operating the light
sources 1232. In addition, constituent elements for operating the
light sources 1232 may be provided. The light source module 1230,
according to the exemplary embodiment of the present inventive
concept, may be substantially identical to the light source module
of FIG. 1. Thus, a detailed description thereof may be omitted.
[0183] The first and second sockets 1240 and 1250 may be provided
as a pair of sockets and may have a structure in which they are
coupled to both ends of a cylindrical cover unit. The cylindrical
cover unit includes the heat radiating member 1210 and the cover
1220. The first socket 1240 may include electrode terminals 1241
and a power supply device 1242. The second socket 1250 may include
dummy terminals 1251 disposed thereon. In addition, an optical
sensor and/or a communications module may be disposed on the
interior one of the first socket 1240 or the second socket 1250.
For example, the optical sensor and/or the communications module
may be installed in the second socket 1250 in which the dummy
terminals 1251 are disposed. In another example, an optical sensor
and/or a communications module may be installed in the first socket
1240 in which the dummy electrode terminals 1241 are disposed.
[0184] A lighting device using a light emitting device may be
classified as an indoor LED lighting device and as an outdoor LED
lighting device. The indoor LED lighting device may mainly be used
in a bulb-type lamp, an LED-tube lamp, or a flat-type lighting
device, as an existing lighting device retrofit. The outdoor LED
lighting device may be used in a streetlight, a safety lighting
fixture, a light transmitting lamp, a landscape lamp, a traffic
light, or the like.
[0185] In addition, a lighting device using LEDs may be utilized as
internal and external light sources in vehicles. When used as the
internal light source, the lighting device using LEDs may be used
as interior lights for motor vehicles, reading lamps, various types
of light source for an instrument panel, and the like. When used as
the external light sources in vehicles, the lighting device using
LEDs may be used in all types of light sources such as headlights,
brake lights, turn signal lights, fog lights, running lights for
vehicles, and the like.
[0186] Further, an LED driving device may be used as a light source
in robots or in various kinds of mechanical equipment. An LED
lighting device using light within a certain wavelength band may
promote the growth of a plant, may change people's moods, or may
also be used therapeutically, as emotional lighting.
[0187] According to exemplary embodiments of the present inventive
concept, an optical device including a light source module may
uniformly distribute brightness and may prevent the occurrence of
Mura defects.
[0188] While the inventive concept has been particularly shown and
described with reference to exemplary embodiments thereof, it will
be apparent to those of ordinary skill in the art that various
changes in form and detail may be made therein without departing
from the spirit and scope of the inventive concept as defined by
the following claims.
* * * * *